Non metal tanning

ABSTRACT

Tanned leather, skin or pelt is produced by non-metal tanning, comprising the step of tanning a bated hide, skin or pelt with a tanning agent (A), the tanning agent (A) being a sulfo-group-containing dichloro-diazine selected from compounds of formula (I), (II), (III) and mixtures of two or more thereof, 
     
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
     
                         
wherein R1 signifies hydrogen, methyl, methoxy, benzoyl, naphthoyl, mono- or di(C 1-4 -alkyl)-aminocarbonyl, C 1-8 -alkoxy-carbonyl or oxy-mono- or oligo-C 2-3 -alkyleneoxy)-carbonyl, R 2 —(SO 3 M) n  signifies a radical of formula (a) or (b),
 
                         
wherein R 3  signifies hydrogen, C 1-8 -alkyl or C 1-8 -alkoxy, m is 1 or 2, n is 1 or 2, and M signifies hydrogen or an alkali metal cation or an ammonium cation, the ammonium cation being a protonated tertiary amine or a quaternary ammonium cation, in a tanning bath, the tanning bath having a pH of from 6 to 10 at the beginning of tanning step.

In the production of leather, the tanning process is of decisiveimportance for the properties and quality of the resulting leather.Among the various tannings known in the art, i.e. mineral, vegetable andsynthetic, chrome-based tannage is a conventional and widely spread wayof tanning which is readily feasible in an industrial scale on mostvarious kinds of skins and hides, and provides tanned leathers withsatisfactory properties (such as high shrinkage temperatures T_(S),suppleness and suitability for subsequent processing such asneutralization, retanning, fat-liquoring, dyeing, finishing).

Chrome-based tanning agents and tannings are however consideredenvironmentally unfriendly and it is therefore desired to provide othertanning methods.

In WO 02/50313 A2 it has been proposed to add certain laccase derivedenzymes to the tanning bath with synthetic or vegetable tanning agentsand then to add an oxidising agent. This adds however some further stepin tanning and furthermore requires a particular precise control of theenzyme activity.

In WO 94/10345 A1 there is described a metal tanning in which in a firststep (a) the substrate is pre-treated with certain compounds of thethere defined formula (1) containing two substituents selected fromcarboxy and hydroxy, and a defined reactive group, and in a second step(b) a metal tannage is applied. Pre-treatment (a) is done in order toimprove tanning with metal tanning agents in subsequent step (b).

In an article by Evans et al. in J.A.L.C.A. Vol. 82 (1987) pages 88-95,mentioned in the introduction of WO 94/10345 A1 and which relates to apre-treatment of certain collagen substrates with 1,2-dicarboxylic acidsand subsequent aluminium tannage, there is described the treatment oflambskin with2-N-[bis-(3′,4′-dicarboxyphenyl)methyl]methylamino-4,6-dichloro-s.triazineand subsequent tannage with basified aluminium sulphate. Also in thisarticle the pre-treatment is done in order to improve tanning with themetal tanning agent (basified aluminium sulphate) in the subsequenttanning step.

J. H. Bowes and C. W. Cater in the article “Crosslinking of Collagen” inJ. Appl. Chem., 15 Jul. 1965, describe some crosslinking tests carriedout on collagen of denatured animal tendon (kangaroo tail tendon, KTT)with various crosslinking compounds—which need not act as completetanning materials in themselves—in particulardifluorodinitrodiphenylsulphone, diisocyanates, a number of aldehydes(formaldehyde, glyoxal, malonic dialdehyde, succinic dialdehyde,glutaraldehyde, adipic dialdehyde, acrolein and dialdehyde starch),cyanuric chloride and a number of cyanuric chloride derivatives (methoxyderivative, amino derivative hydrochloride, sulphonate derivative sodiumsalt, 5-sulphonaphth-1-ylamino derivative sodium salt, andbis-4,4′-diaminostilbene-2,2′-disulphonic acid derivative sodiumsalt)—in order to assess their crosslinking potentiality, and whichcould be combined with conventional tanning materials for improvingresistance to deterioration due to moist heat and perspiration. Fromtheir measurements, finally, they conclude that aldehydes(glutaraldehyde) appear to be most promising because of number ofcrosslinks and stability, whereas cyanuric chloride derivatives would beless useful as crosslinking agents in collagen.

It has now surprisingly been found that a non-metal tanning ofoutstanding quality can be achieved using the below defined tanningagents—in particular even as complete tanning materials—and tanningmethods, which also allow to omit a pickling as conventionally carriedout before chrome tanning or aldehyde tanning, unless necessary forother reasons e.g. for degreasing. The invention relates to the tanningprocess, the defined tanning agent compositions, the use of the tanningagents and their compositions, the tanned leather, skin or pelt and itsuse for further processing.

As a non-metal tanning process there is meant herein a tanning producedwithout using any cationic metal compounds which have tanning activity,i.e. polybasic metal compounds, mainly chromium, aluminium, iron,zirconium or titanium salts etc. As a non-metal tanning agent there ismeant herein a tanning agent that does not comprise any cationic metalcompounds of tanning activity, i.e. polybasic metal compounds, mainlychromium, aluminium, iron, zirconium or titanium salts, etc.

In the following, alkyl means linear or branched alkyl, if not otherwisestated.

The invention thus firstly provides a process for the production oftanned leather, skins or pelts by non-metal tanning, comprising the stepof tanning a bated hide, skin or pelt with a tanning agent (A), thetanning agent (A) being a sulpho-group-containing dichloro-diazineselected from compounds of formula (I)

of formula (II)

and of formula (III)

and mixtures of two or more thereof,wherein

-   R1 signifies hydrogen, methyl, methoxy, benzoyl, naphthoyl, mono- or    di(C₁₋₄-alkyl)aminocarbonyl, C₁₋₈-alkoxy-carbonyl or oxy-mono- or    oligo-(C₂₋₃-alkyleneoxy)-carbonyl-   R2-(SO₃M)_(n) signifies a radical of formula

-   R3 signifies hydrogen, C₁₋₈-alkyl or C₁₋₈-alkoxy,-   m is 1 or 2,-   n is 1 or 2    and-   M signifies hydrogen or an alkali metal cation or an ammonium    cation, the ammonium cation being a protonated tertiary amine or a    quaternary ammonium cation,    in a tanning bath, the tanning bath having a pH of from 6 to 10 at    the beginning of tanning step.

In formulae (I) and (II) the bracket around the right hand part of thebicyclic system is meant to indicate that the m sulphonic group orgroups are attached to a corresponding number of carbon atoms of thebenzo ring shown within the bracket, or/and to the R1 residue.

The C₁₋₈-alkyl or C₁₋₈-alkoxy groups preferably are C₁₋₄-alkyl orC₁₋₄-alkoxy, more preferably ethyl or ethoxy or most preferably methylor methoxy. The alkoxy groups may also be oligoalkyleneoxy chains whichcontain two to ten alkyleneoxy units, preferably 2 to 7 alkyleneoxyunits, the alkylene units having 2, 3 or 4 carbon atoms.

The tanning agent (A) may consist of more than one compound of formula(I) and/or (II) and/or (III).

Where M is an alkali metal cation or a ammonium cation, then it may beany alkali metal cation or an ammonium cation as conventionally employedfor salt formation in anionic compounds.

Preferably, the alkali metal cation is selected from the groupconsisting of lithium, sodium and potassium, more preferably the alkalimetal cation is sodium.

Preferably, the ammonium cation is a cation of formula (Ic),

wherein

-   R10, R11, R12 and R13 are same or different and independently from    each other selected from the group consisting of H, C₁₋₄-alkyl,    C₂₋₃-hydroxyalkyl and benzyl, with the proviso, that only one of the    four substituents R10, R11, R12 and R13 may be H.    Preferably,-   R10 is H or C₁₋₄-alkyl, and-   R11, R12 and R13 are same or different and independently from each    other selected from the group consisting of C₁₋₄-alkyl,    C₂₋₃-hydroxyalkyl; or-   R10, R11, R12 and R13 are same or different and independently from    each other are C₁₋₄-alkyl; or-   R10, R11 and R12 are same or different and independently from each    other are C₁₋₄-alkyl or C₂₋₃-hydroxyalkyl, and-   R13 is benzyl.

More preferably, the ammonium cation is selected from the groupconsisting of monohydrogen-tri(C₂₋₃-alkanol)-ammonium,tetra(C₁₋₄-alkyl)-ammonium, tri(C₁₋₄-alkyl)-mono(C₂₋₃-alkanol)-ammonium,di(C₂₋₃-alkanol)-di(C₁₋₄-alkyl)-ammonium,mono(C₁₋₄-alkyl)-tri(C₂₋₃-alkanol)-ammonium,monobenzyl-tri(C₁₋₄-alkyl)-ammonium andmonobenzyl-tri(C₂₋₃-alkanol)-ammonium.

Especially, the ammonium cation is a quaternary ammonium cation.

More especially preferably, M is an alkali metal cation, even moreespecially preferably M is sodium.

If in formulae (I) or (II) R1 is hydrogen, methyl, methoxy,C₁₋₈-alkoxy-carbonyl or mono- or di(C₁₋₄-alkyl)-aminocarbonyl thecompounds of formulae (I) and (II) more particularly are of formula(Ia1) and (IIa1)

wherein R4 is hydrogen, methyl, methoxy, C₁₋₈-alkoxy-carbonyl or mono-or di(C₁₋₄-alkyl)-aminocarbonyl.

If in formula (I) or (II) R1 is benzoyl or naphthoyl the compounds offormula (I) or (II) more particularly are of formula

wherein

-   m1 is 0 or 1 and-   m2 is 0 or 1    with the proviso that m1+m2 is 1 or 2.

If in formula (I) or (II) R1 is oxy-mono- oroligo-(C₂₋₃-alkyleneoxy)-carbonyl the compounds of formula (I) or (II)more particularly are of formula

wherein

-   q is 1 to 10 and-   m3 is 0 or 1.

Preferably, compound of formula (I) is a compound of formula (I-I),

Preferably, compound of formula (II) is a compound of formula (II-I)

Preferably, compound of formula (III) is a compound of formula (III-I)

wherein n is 1 or 2, more preferably 1.

More preferably, compound of formula (III) is a compound of formula(III-II)

The compounds of formula (I) and (II) are known or may be producedaccording to known methods, preferably by sulphonation of a compound offormula (IV),

or respectively (V)

wherein

-   R5 signifies hydrogen, methyl, methoxy, benzoyl, naphthoyl, mono- or    di-(C₁₋₄-alkyl)-aminocarbonyl, C₁₋₈-alkoxy-carbonyl or hydroxy-mono-    or -oligo-(C₂₋₃-alkyleneoxy)-carbonyl

The compounds of formula (III) are known or may be produced according toknown methods, preferably by sulphonation of a compound of formula (VI),

wherein R6 signifies a radical of formula

Sulphonation may be carried out under conditions conventional per se,e.g. with concentrated sulphuric acid (preferably of 98% w/wconcentration) or oleum at temperatures above 120° C., preferably in therange of 130-240° C., as suitable for achieving the desired degree ofsulphonation. Upon completion of the sulphonation reaction the producedsulphonic acids may be reacted with a base for salt formation

The base which can be used for salt formation and pH adjustment aftercompletion of the sulphonation reaction, is preferably selected from thegroup consisting of alkali metal base, quaternary ammonium hydroxide andcarbonate.

The alkali metal base is preferably selected from the group consistingof hydroxide, carbonate and bicarbonate of lithium, sodium and potassiumand mixtures thereof.

The quaternary ammonium hydroxide and carbonate is preferably selectedfrom the group consisting of hydroxide and carbonate oftetramethyl-ammonium, tetraethyl-ammonium and benzyl-trimethyl-ammonium.

The compounds of formulae (I) and/or (II) may be used in salt form, thesalt form being preferably an alkali metal salt of the sulphonic acid,more preferably a sodium salt. The compounds of formulae (I) and/or (II)in salt form are in general soluble in water and they are suitablyemployed in the form of an aqueous solution or dispersion (atconcentrations higher than the one corresponding to the saturatedsolution), preferably in an amount of from 2 to 70% by weight, morepreferably 10 to 50% by weight, the % weight being based on the totalweight of the solution or dispersion of compound of formulae (I) and/or(II). Preferably this solution or dispersion contains also a dispersingagent (B) as mentioned above, in a concentration as mentioned abovesuitable for dispersing compounds of formulae (I) and/or (II) when thelatter are added as a dry product and are stirred into the solution.

The surfactant (B) is preferably selected from the group consisting of

-   (B1) non-ionic surfactant,-   (B2) anionic surfactant,-   (B3) amphoteric surfactant and    mixtures of two or more thereof,    with the proviso that the surfactant (B) does not have a substituent    capable of reacting with the compound of formula (II) under the    chosen reaction conditions, in particular does not have a primary or    secondary amino group. Preferable mixtures are mixtures of (B2) with    (B1) and/or (B3), or of (B1) with (B3).

Preferably, the non-ionic surfactant (B1) is selected from the groupconsisting of oligo- or polyglycolethers of aliphatic alcohols, oligo-or polyglycolesters of aliphatic carboxylic acids, oxyalkylated fattyacid amides and oxyalkylated partial esters of glycerol or sorbitol withfatty acids.

Preferably, the oxyalkylation of the fatty acid amides and theoxyalkylation of the partial esters of glycerol or sorbitol with fattyacids leads to oligo- or polyglycolether chains.

Preferably any oligo- or polyglycolether chain contains 2 to 60, morepreferably 2 to 24 oxyalkylene units which are oxyethylene andoptionally oxypropylene units, and preferably at least 40 mol-%, morepreferably at least 50 mol-% being oxyethylene units and preferably, thenon-ionic surfactant (B1) contains at least two oxyethylene units.

Preferably, the lipophilic aliphatic radical in the aliphatic alcohol,aliphatic carboxylic acids, fatty acid amides and fatty acids contain 8to 24 carbon atoms. The aliphatic radical may be saturated orunsaturated (preferably it contains only one double bond) and may belinear or branched, the branched preferably saturated.

As examples of aliphatic alcohols there may be mentioned lauryl, cetyl,myristyl, stearyl or oleyl alcohol, and C₉₋₁₅-oxoalcohols.

As examples of aliphatic carboxylic acids and of fatty acid amides theremay be mentioned lauric, palmitic, myristic, stearic, behenic, arachicor oleic acid or amide.

The oligo- or polyglycolethers of aliphatic alcohols may be produced byoxyethylation and, if oxypropylene units are also to be present,oxypropylation of the corresponding aliphatic alcohols.

The oxyalkylated fatty acid amides may be produced e.g. byoxyethylation, and if oxypropylene units are also to be present, byoxypropylation of the corresponding fatty acid amides, e.g. of aliphaticacid diethanolamide or diisopropanolamide.

Oligo- or polyglycolesters and sorbitol monoesters may e.g. be producedby esterification of a corresponding oligo- or poly-ethylene- andoptionally -propylene-glycolether or sorbitol. Monoglycerides may bepartial saponification products of corresponding naturally occurringtriglycerides.

Preferably, the anionic surfactant (B2) is selected from the groupconsisting of anionic polycarboxylates, aliphatic fatty acids in saltform (soaps), methyltaurides of aliphatic fatty acids and anionicderivatives of non-ionic surfactants, preferably of non-ionicsurfactants (B1), in particular carboxymethylation products orcarboxyethylation products of non-ionic surfactants (B1) or sulphuricacid monoesters or phosphoric acids monoesters of non-ionic surfactants(B1), in particular in alkali metal salt form.

Preferred anionic polycarboxylates are polyacrylates andpolymethacrylates.

Preferably, the amphoteric surfactants (B3) are betaines orsulphobetaines or anionic derivatives of cationic surfactants which maybe selected from the group consisting of tertiary or preferablyquaternary derivatives of fatty amines, e.g. with 8 to 24 carbon atomsin the fatty amine chain, and in which the substituents of the tertiaryamino group or quaternary ammonium group are C₁₋₄ alkyl (preferablymethyl or ethyl) or hydroxyl-C₁₋₄-alkyl (preferably ethanol orisopropanol) and optionally benzyl, and where, if desired, the tertiaryamino group or quaternary ammonium group may also contain an oligo- orpolyglycolether chain analogously as mentioned above in the non-ionicsurfactants (B1). As examples of fatty amines there may be mentionedlauryl, cetyl, myristyl, stearyl or oleyl amine and the amino group maybe substituted with two methyl or ethyl groups and optionally a methylor benzyl group, or with three methyl or ethyl groups or with twoethanol groups. If the tertiary amino group or quaternary ammonium groupis oxyalkylated it may preferably contain a total of 2 to 40, morepreferably 2 to 24 alkylenoxy groups, preferably at least 40 mol-% ofwhich are ethyleneoxy and the remaining are propylenoxy. Tertiary aminogroups are preferably protonated e.g. with hydrochloric, phosphoric orC₂₋₂₀-, preferably C₂₋₅-alkanoic acid. These anionic derivatives ofcationic surfactants are e.g. carboxymethylation or carboxyethylationproducts, sulphuric or sulphamic acid monoesters or phosphoric acidmono- or diesters of those cationic surfactants containing a hydroxygroup.

Preferably, the surfactant (B) is a non-ionic surfactant (B1).

Preferably non-ionic surfactants (B1) are used, more preferably thenon-ionic surfactants (B1) are compounds of formula (VII)(polyglycolethers),R7-O—(C₂₋₃-alkylene-O)_(r)—H  (VII)wherein

-   R7 signifies C₈₋₂₄-alkyl or C₈₋₂₄-alkenyl,-   C₂₋₃-alkylene is selected from the group consisting of —CH₂—CH₂—,    —CH₂—CH(CH₃)—, —CH(CH₃)—CH₂— and combinations thereof, preferably of    —CH₂—CH₂—, —CH₂—CH(CH₃)— and combinations thereof,-   r signifies 2 to 60,    in case that the non-ionic surfactant (B1) of formula (VII) consists    of more than one compound of formula (VII), r may also be calculated    and expressed as the average number of radicals of the formula (VII)    in the mixture, with the proviso that the compound of formula (VII)    contains at least two ethyleneoxy units, and with the proviso that    at least 40% of the total number of alkyleneoxy units in the    compound of formula (VII) are ethyleneoxy.

If desired, the product may be dissolved or dispersed in water. If a dryproduct is desired, this may be obtained from an aqueous solution ordispersion of the reaction product in a manner conventional per se, e.g.by precipitation (e.g. by salting out) and filtration, or by evaporationunder controlled conditions.

A tanning agent (A) comprising more than one compound of formulae (I)and/or (II) and/or (III) can be produced by physical mixing of more thanone compound of formula (I) and/or (II) and/or (III). The physicalmixing can be done in dry form and/or in dissolved or dispersed form,preferably in dissolved or dispersed form in water.

The tanning agent (A) may be used as such, as produced, preferably indry form or more preferably in the form of an aqueous solution ordispersion.

According to a particular aspect of the invention, the tanning agent (A)is in the form of an aqueous composition (T) which is free of anymetal-based compounds which have tanning activity, aqueous composition(T) comprising the tanning agent (A) and water, and preferably comprisesin addition the surfactant (B).

Therefore, another subject of the invention is a tanning process asdescribed above, also with all its preferred embodiments, wherein thetanning agent (A) is employed in the form of an aqueous composition (T)which is free of metal compounds of tanning activity.

More preferably, the composition (T) comprises of from 2 to 70% byweight, especially 10 to 50% by weight, the % by weight based on thetotal weight of the composition (T), of tanning agent (A).

Where surfactant (B) is present in the composition (T), the weight ratioof surfactant (B) to tanning agent (A) in the composition (T) ispreferably of from 0.001 to 1, more preferably of from 0.002 to 0.4,even more preferably of from 0.005 to 0.1.

Preferably, in the composition (T), the surfactant (B) is the non-ionicsurfactant (B1). If an anionic or amphoteric surfactant (B2) or (B3) isused, its amount is preferably of from 0.001 to 10 mol-%, the mol-% withrespect to the total molar amount of tanning agent (A). More preferablythe surfactant (B) is only the non-ionic surfactant (B1). If surfactant(B2) is a polycarboxylate, its amount is preferably <5% by weight, morepreferably of from 0.01 to 4% by weight, even more preferably from 0.05to 2% by weight, the % by weight being always based on the total weightof tanning agent (A).

The composition (T) has preferably an acidic to neutral pH, morepreferably it has an acidic pH. For pH adjustment, a suitable buffer maybe employed and composition (T) thus preferably further comprises abuffer (C1) to keep an acidic to neutral pH, preferably to keep anacidic pH, more preferably to keep a pH of from 1 to 7, even morepreferably to keep a pH of from 1 to 5.

The buffer (C1) is preferably selected from the group consisting ofphthalate, oxalate and citrate of sodium and/or of potassium, mono- anddi-hydrogenphosphate of sodium and/or of potassium, mixture ofphosphoric acid and di-hydrogenphosphate of sodium and/or potassium andmixtures thereof, preferably a combination of KH₂PO₄ or NaH₂PO₄ andNa₂HPO₄ or K₂HPO₄.

The amount of buffer (C1) in the composition (T) is preferably chosen soas to achieve the desired pH mentioned above. The amount of buffer (C1)is preferably of from 0.1 to 5% by weight, the % by weight being basedon the total weight of the composition (T).

Compositions (T) advantageously may further comprise

-   an agent (D) to protect against the damaging action of    microorganisms,-   preferably, agent (D) is a bacteriostatic additive and/or a    microbicide, e.g. a fungicide.

As agent (D) there may be employed commercially available products,which may be employed in small concentrations, in particular accordingto the commercially recommended ones. The amount of agent (D) in thecomposition (T) is preferably of from 0 to 10% by weight, morepreferably of from 0.01 to 10% by weight, even more preferably of from0.02 to 1% by weight, the % by weight being based on the total weight ofthe composition (T).

According to a particular further feature of the invention, aqueouscompositions (T) may further comprise

-   a polysaccharide-based thickener (E).

As thickener (E) there may be employed products known per se, inparticular gums, carbohydrates, carbohydrate derivatives, e.g. pectinsand hydrophilic cellulose derivatives, which with water form viscoussolutions (colloidal or true solutions). There may be mentioned gums asobtainable by fermentation and optionally chemical modification ofnatural plant-exudates, e.g. xanthan gum, tragacanth gum, guar gum,carrageenan gum, alginate gum, agar gum, gum ghatti, and water solublecarbohydrate derivatives in particular pectins, e.g. pectins from fruits(e.g. citric fruits or apples) and amylopectins (e.g. from corn starchor potato starch), and hydroxyethylcellulose. The gums, carbohydratesand carbohydrate derivatives may also be chemically modified, providedthat they do not contain any substituents capable of reacting withtanning agent (A) under storage or application conditions, in particularthey do not contain any basic aminogroups, especially any primary orsecondary amino groups.

Thickener (E) may be employed in a minor proportion in the composition(T), in particular as suffices for adjusting the viscosity of (T) sothat it is still flowable. Where thickener (E) is employed in thecomposition (T), it is added preferably in such a concentration that theviscosity of the composition (T) at 20° C. is preferably ≦50,000 mPa·s,more preferably of from 200 to 10,000 mPa·s, even more preferably offrom 300 to 2,500 mPa·s, especially preferably 600 to 1,500 mPa·s. Theviscosity is the Brookfield rotational viscosity, spindle no. 3, 20 rpm.

Preferably the amount of thickener (E) in the composition (T) is of from0 to 5% by weight, more preferably of from 0.1 to 5% by weight, the % byweight based on the total weight of the composition (T).

Preferred compositions (T) are compositions (T1) comprising, in additionto the tanning agent (A), surfactant (B) and/or buffer (C1), morepreferably surfactant (B) or surfactant (B) and buffer (C1); preferablycompositions (T1) further comprise an agent (D) and/or a thickener (E).

Therefore, another preferred embodiment of the invention is a tanningprocess as described above, also with all its preferred embodiments,wherein the composition (T) is an aqueous composition (T1) comprisingthe tanning agent (A) and further comprising a surfactant (B) and/or abuffer (C₁) to keep an acidic to neutral pH.

Therefore, another preferred embodiment of the invention is a tanningprocess as described above, also with all its preferred embodiments,wherein the composition (T) is an aqueous composition (T1) of a tanningagent (A) comprising a surfactant (B) and/or a buffer (C₁) and furthercomprising an agent (D) to protect against the damaging action ofmicroorganisms and/or a polysaccharide-based thickener (E).

Preferably, the composition (T) is a composition (T1) comprising

-   of from 2 to 70% by weight, preferably 10-50% by weight, of tanning    agent (A), the % by weight based on the total weight of the    composition (T1);-   surfactant (B) in a weight ratio of surfactant (B) to tanning    agent (A) of from 0.001 to 1, more preferably of from 0.002 to 0.4,    even more preferably of from 0.005 to 0.1;-   buffer (C1) in such an amount as to achieve a pH in the composition    (T1) of from 1 to 7, more preferably pH 1 to 5, the amount of buffer    (C1) preferably being of from 0.1 to 5% by weight, the % by weight    being based on the total weight of the composition (T1);-   of from 0 to 10% by weight, preferably of from 0.01 to 10% by    weight, more preferably of from 0.02 to 1% by weight, of agent (D),    the % by weight being based on the total weight of the composition    (T1),-   thickener (E) in such an amount that the viscosity of the    composition (T1) at 20° C. (Brookfield rotational viscosity measured    with spindle no. 3, at 20 rpm) is ≦50,000 mPa·s, preferably of from    200 to 10,000 mPa·s, more preferably of from 300 to 2,500 mPa·s,    even more preferably 600 to 1,500 mPa·s, especially thickener (E) is    used in an amount of from 0 to 5%, more preferably of from 0.1 to 5%    by weight, the % by weight being based on the total weight of the    composition (T1);-   and the dry substance content of the composition (T1) is preferably    of from 4 to 75% by weight, more preferably in the range of 10 to    60% by weight, the % by weight based on the total weight of the    composition (T1).

The dry substance content of (T) or (T1) may be assessed in a mannerconventional per se, e.g. by calculation based on the employed reactantsand components—mostly by simple addition of the amounts of thesubstances (expressed in dry form) added for the production of (T) or(T1) and subtracting any water formed during the reaction—, or, which isthe preferable way, by subtracting the water content determined in aconventional way, e.g. by titration, e.g. Karl Fischer titration, fromthe total weight of (T) or (T1).

Particularly preferably, composition (T) or (T1) is a composition (T2)which contains the thickener (E), preferably in an amount of 0.1% byweight, more preferably of from 0.1 to 5% by weight of (E), the % byweight based on the total weight of the composition (T2). The viscosityof the composition (T2) at 20° C. (Brookfield rotational viscositymeasured with spindle no. 3, at 20 rpm) is preferably in the range of300 to 2,500 mPa·s, more preferably 600 to 1,500 mPa·s.

This composition (T2) is of satisfactory stability and is suitable forstorage and shipment and is directly usable. It is readily dilutablewith water and may be directly metered into the tanning drum, ifdesired.

As a substrate for the treatment with tanning agent (A), in particularfor tanning, there may be used any conventional animal hides, skins andpelts as are in general employed for tanning, e.g. hides from cow, calfor buffalo (e.g. also as split hides), skins from goat, sheep or pig,buckskins and pelts; but also other hides and skins e.g. from othermammals (foal, camel, lama, kangaroo, wallaroo, wallaby), reptiles(snakes, lizards), fishes (shark) or birds (ostrich), woolled skins andfurskins, may be used in the process of the invention.

The bated substrates (animal hides, skins or pelts) may have beenprocessed in the beamhouse before tanning, i.e. trimmed, soaked, limed,delimed and bated in conventional way. Before deliming the limed hides,skins or pelts are usually fleshed and, if required, split andoptionally scudded, shaved etc. and, if required, defatted and/ordehaired.

Bated hides, skins and pelts to be used as substrates in the process ofthe invention may have been produced in conventional way, in thebeamhouse, in particular by deliming the limed substrates and bating,using known agents for each of the mentioned processing steps.

Deliming may have been carried out in conventional way with knowncompounds such as acids, ammonium salts of low molecular aliphaticcarboxylic acids, ammonium sulphate or sodium phosphate. Optionally thedeliming composition may contain an enzyme e.g. as mentioned below, sothat, if desired, bating and deliming may at least in part be combined.

For bating there may be employed known proteolytic bates, in particularin the form of bating compositions based on conventional proteolyticenzymes, mainly bacterial proteases, fungal proteases, and pancreasenzyme. Occasionally also other enzymes may be employed, such aslipases, amylases and also other hydrolases. Pancreas enzyme alone or inadmixture with other enzymes (e.g. lipases, amylases and also otherhydrolases) is preferred. Commercial forms of such enzymes may beformulated together with other components, especially with some mineralcarriers, saccharides or polysaccharides and/or a hydrotrope. For thepurpose of the invention substrates conventionally bated with batingcompositions based on pancreas enzyme are well suitable.

The above bating compositions are in particular of an optimum activityin the weakly basic pH range, more particularly at a basic pHs ≦11, andconsequently the pH of the bated substrate is preferably in the weaklybasic range, in particular a pH in the range of 7.5 to 11, morepreferably 7.5 to 10.

Where the substrate has been delimed with acids, also acidic bates maybe used, e.g. pepsins e.g. in the form of a solution of 2% pepsin inwater and at a pH in the range of 3-4.

The tanning process of the invention is based on a true tanning with thetanning agent (A) leading to leathers, skins and pelts withcharacteristic true tannage properties, such as a reduction orelimination of swellability, reduction of deformability and augmentationof firmness, diminution of shrinkage in volume, surface and thickness bydrying, and increment of the porosity of the fibre texture, and furtherrising of shrinkage temperature and fastness of the collagen fibre tohot water, and of being non-rotting.

As a “step” in the tanning process according to the invention there ismeant any tanning step in a tanning process in which the tanning agent(A) acts on the non-tanned or not fully tanned substrate, i.e.pre-tanning, main tanning, or full or complete tanning (including also acombined tanning). The tanning agent (A) can thus be employed forpre-tanning, for main tanning, or for full (i.e. complete) tanning orfor both pre-tanning and main tanning, and for combined tannings. Theuse of the tanning agent (A) as a full tanning agent or as both apre-tanning agent and a main tanning agent is however the most relevantaspect of the invention.

The tanning process of the invention—which may be a one stage tanning,i.e. a full tanning, or a two stage tanning, i.e. a pre-tanning followedby a main tanning, or a combined tanning—can be carried out directlyafter bating.

The tanning process with the tanning agent (A) of the invention may becarried out in an aqueous, aqueous/organic or organic medium; suitableorganic media include e.g. ethanol, isopropanol, acetone,methylethylketone, dimethylsulphoxide, chloroform, chlorobenzene andtoluene. Preferably it is carried out in an aqueous bath, e.g. at a bathlength of 30 to 400% by weight of water, preferably 40 to 200%, mostpreferably 40 to 100%, the % by weight based on the weight of thefleshed or (if the hide has been split) the split substrate, and attemperatures preferably of from 10 to 50° C., more preferably of from 10to 40° C., even more preferably of from 15 to 40° C. Preferably tanningis begun at a temperature of from 10 to 35° C., more preferably of from15 to 30° C., and at the end the temperature is allowed to raisepreferably by 5 to 20 degrees, more preferably by 8 to 15 degrees, to anend temperature of from 20 to 40° C., preferably of from 25 to 40° C.

For the tanning process of the invention the tanning agent (A) is addedin the tanning bath in an efficient concentration, preferably of from0.5 to 20% by weight, more preferably of from 1 to 10% by weight, the %by weight being based on the weight of the fleshed or split substrate.The tanning agent (A) may be added in dry form or preferably in the formof an aqueous composition, preferably as mentioned above as acomposition (T).

With particular preference a surfactant, in particular as mentionedabove a surfactant (B), preferably a non-ionic surfactant (B1), and/or abuffer (C2) for nearly neutral to basic pH values, in particular pH≦6,may be added in the tanning bath, in a weight ratio as suitable in orderto achieve the desired pH at the beginning of the tanning step.

Therefore, another preferred aspect of the invention is a tanningprocess as described above, also with all its preferred embodiments,wherein the tanning bath comprises a buffer (C2) to achieve a nearlyneutral to basic pH at the beginning of the tanning step.

As buffers (C2) there may be employed known buffers, preferably selectedfrom the group consisting of sodium and/or of potassium bicarbonate,sodium and/or of potassium carbonate, sodium and/or of potassiumhydrogen phosphate, sodium borate and trishydroxymethylaminomethane.Preferably buffer (C2) is a combination of KH₂PO₄ or NaH₂PO₄ and K₂HPO₄or Na₂HPO₄. For the tanning process of the invention it is of particularadvantage to employ compositions (T) as described above, whichpreferably already contain a surfactant (B) and optionally also agent(D) and/or thickener (E). The buffer (C2) may be added directly into thetanning bath. Preferably the buffer (C2) is added in a two-stage tanningbefore the main tanning step in order to set the pH of the main tanningbath. Compositions (T), in particular compositions (T1), are readilyefficient for tanning. The composition may contain some salt asresulting as a by-product from the sulphonation reaction followed byaddition of a base.

The tanning process of the invention is started at a pH of from 6 to 10,preferably of from 6 to 9, more preferably of from 6.5 to 8.5, inparticular as suitable for inducing the reaction of tanning agent (A)with the substrate.

During the tanning, the pH gradually decreases spontaneously by a few pHunits, in particular by from 1 to 4 pH units, to a pH in the nearlyneutral to weakly acidic pH range, in particular to a pH of from 7 to3.5, preferably of from 6.5 to 3.5. The process may thus be carried outunder self-regulating pH conditions. If desired, however, the tanningreaction may be influenced by the addition of a minor proportion of acid(e.g. a mineral acid, e.g. sulphuric or phosphoric acid, or a lowmolecular carboxylic acid e.g. with 1 to 4, preferably 1 or 2, carbonatoms, e.g. formic or acetic acid), or by the addition of a minorproportion of base (alkali), e.g. in order to accelerate or deceleratethe reaction and/or to shift the pH slightly towards more neutralvalues.

In the process of the invention pickling is in principle not necessaryand may mostly be omitted. Therefore, subject of the invention is also atanning process as described above, also in all its preferredembodiments, wherein the bated hide or skin or pelt is subjected totanning with a tanning agent (A) without previous pickling.

If desired, however, e.g. in order to obtain a certain consistency ofthe substrate or if the substrate is to be defatted under acidicconditions before tanning, a pickling may be carried out. The pickledsubstrate may be defatted in conventional way. Sometimes commerciallyavailable hides have already been pickled. If the substrate has beenpickled, it is suitably depickled before tanning in order to achieve thedesired pH in the range of 6 to 10. Therefore, another subject of theinvention is a tanning process as described above, also with all itspreferred embodiments, wherein a bated and pickled hide, skin or pelt isdepickled to a pH in the range of 6 to 10 before tanning with a tanningagent (A).

A depickling may be carried out as suitable to achieve pH values in therange of 6 to 10, preferably 6 to 9, by employing a correspondingquantity of base for depickling. Depickling may be carried out inconventional manner using known compounds, e.g. sodium and/or potassiumbicarbonate or/and formate, and under conditions conventional per se,e.g. at bath lengths in the range of 50 to 400% by weight of water, the% by weight being based on the the weight of the fleshed or (if the hidehas been split) the split substrate, at temperatures in the range of 10to 30° C. and rotation in the drum for 60 minutes to 6 hours. Ifdesired, e.g. to ensure depickling also in the interior of thesubstrate, the substrate may be kept in the depickling bath e.g. bydwelling overnight, optionally with intermittent drum rotation, e.g. 5to 15 minutes every hour.

If the tanning process is started at nearly neutral conditions, inparticular at a pH in the range of 6 to 7.5,—especially when usingpickled and depickled substrates—the pH may initially also be kept inthis range or increased, to give a pH in the range of 6 to 9, byaddition of a base.

If—as preferred—no pickling and depickling is carried out, pretanning orfull tanning may be carried out directly on the bated substrate. The pHat the beginning of the tanning process is preferably nearly neutral tobasic, in particular in the range of 6.5 to 10, preferably 6.8 to 9, andduring the treatment gradually decreases spontaneously by a few pHunits, in particular by 1 to 4 pH units, to a nearly neutral to weaklyacidic pH range, in particular 7 to 4, preferably 6.5 to 4.5. Thetemperature is preferably in the range of 10 to 40° C., more preferably15 to 35° C. More particularly tanning is preferably begun at 10 to 30°C. more preferably 15 to 25° C., and at the end the temperature isallowed to rise by 5 to 20 degrees, preferably by 8 to 15 degrees, to 20to 40° C., preferably 25 to 40° C.

The tanning process of the invention is very simple and may be carriedout in a relatively short time, in particular within about 5 to 24hours, preferably 6 to 12 hours.

After tanning the exhausted tanning bath may be drained off and thetanned leather, skin or pelt may be rinsed or washed e.g. one to threetimes with water (e.g. 100 to 600% by weight of water, preferably 250 to400% by weight of water, the % by weight being based on the weight ofthe fleshed or (if the hide has been split) the split substrate), towhich if desired some conventional surfactants may be added, in order tofavour slippage of the grain. If desired also a biocide e.g. asmentioned above for (D), may be added during the process, e.g. into thelast washing bath, as a preserving agent for the resulting tanned hideor skin or pelt.

If desired a further non-mineral tanning agent (F), which is differentfrom (A), of anionic or/and ethylenically unsaturated character or/andcontaining groups of basic character may be applied before, after ortogether with tanning agent (A) in pre-tanning, in main tanning or infull tanning, preferably for pre-tanning before a main tanning with (A),or in combination with (A) in a main or full tanning, or/and preferablyfor a complementary tanning after a main or full tanning with (A), oreven for retanning.

-   (F) preferably is selected from the group consisting of-   (F1) a vegetable tanning agent,-   (F2) a syntan,-   (F3) a synthetic, semisynthetic or natural resin or polymer,-   (F4) a tanning natural oil or modified oil,-   (F5) a compound of formula (VIII)

-   -   wherein    -   p is 1 or 2 and    -   M is as defined above,

-   (F6) a tanning oxazolidine, in particular of formula (IX) or (X)

andmixtures of two or more thereof.

As vegetable tanning agents (F1) there may be employed known vegetabletanning agents, in particular pyrogallol- or pyrocatechin-based tannins,e.g. valonea, mimosa, teri, tara, oak, pinewood, sumach, quebracho andchestnut.

As syntans (F2) there may be employed known synthetic tanning agents, inparticular syntans derived from sulphonated phenols and/or naphthols,and/or sulphones or polymers of sulphones and/or sulphonated phenolsand/or sulphonated naphthols with formaldehyde or acetaldehyde andoptionally urea, among which sulphone-based products are preferred.

As synthetic or semisynthetic or natural resins or polymers (F3) theremay be employed e.g. known polyacrylates, polymethacrylates, copolymersof maleic anhydride and styrene, condensation products of formaldehydewith melamine or dicyandiamide, lignins and natural flours. Among thesynthetic or semisynthetic or natural resins or polymers (F3), those ofanionic character (e.g. polyacrylates, polymethacrylates, ligninsulphonates and copolymers of maleic anhydride and styrene) and whichare free of basic amino groups are designated herein as (F3-I).

As natural or modified oils (F4) there may be employed known naturaltriglycerides, e.g. rape seed oil, fish oils or their oxidisedderivatives, sulphated, sulphonated or oxy-sulphited fish oils, or theiroxidised derivatives, or surrogates thereof.

As compounds (F5) there may be employed compounds in which p is 1 or 2,or mixtures compounds in which p is 1 and p is 2.

Tanning with (A) may be carried out as a full tanning, or as apre-tanning before a non-metal main tanning, which may be carried outwith a vegetable tanning agent or with a synthetic tanning agent otherthan (A)—e.g. as mentioned above as (F)—or also with a tanning agent (A)according to the invention, or as a main tanning after a non-metal oreven non-mineral pre-tanning (which may be vegetable or synthetic) e.g.carried out with (F) mentioned above. Where the tanning with (A) of theinvention is carried out as a main tanning subsequently to a vegetablepre-tanning or to a synthetic pre-tanning with syntans, the pH may ifrequired be adjusted to the desired value between 6 and 10, e.g. byaddition of an alkali metal carbonate, bicarbonate or formate for thetanning method of the invention.

According to a particular feature of the invention, the tanning agent(A) may be used in combination with another non-mineral tanning agent(F), preferably (F-I), (F-I) being selected from the group consisting of(F1), (F2) and (F3-I), e.g. in a weight ratio of (A) to (F-I) being inthe range of from 0.05:1 to 20:1, more particularly from 2:1 to 10:1.The concentration of the combined tanning agents may be as desired forachieving a defined tanning, e.g. of from of 0.5 to 20% by weight,preferably 1 to 10% by weight, the % by weight based on the weight ofthe fleshed substrate.

According to a further particularly preferred feature of the invention,the substrates are first tanned in one or two stages with (A) and thenare subjected to a complementary tanning with a non-mineral tanningagent (F), which preferably is (F-II), (F-II) being selected from thegroup consisting of (F1), (F2), (F3) and (F5). As a complementarytanning there is intended here an additional tanning step carried outafter main or full tanning with (A), and which substantially does notmodify the characteristic kind of properties of the leather, skin orpelt tanned with (A), but may improve some of the typical tannageproperties. Typically it is carried out with a smaller amount of thecomplementary tanning agent (F) compared with the amount of the employedmain or full tanning agent (A), preferably 5 to 80% by weight,preferably 10 to 60% by weight of (F), the % by weight based on theweight of the employed amount of (A). This complementary tanning mayadvantageously be carried out sequentially to the tanning with (A) undertemperature conditions as mentioned above, e.g. 10 to 40° C., at bathlengths preferably as used for tanning with (A), e.g. in the range of 40to 200% by weight of water, the % by weight being based on the weight ofthe fleshed or (if the hide has been split) the split substrate, andunder pH conditions as resulting from the tannage with (A), preferablyafter rinsing with water, usually this pH may range in the scope of 4 to7.

Complementary tanning with (F), preferably with (F-II), may be carriedout in the tannery directly after tanning, or even after having rinsed,dried and optionally mechanically treated the tanned leather, skin orpelt.

At the end of the tanning process, after draining off of the exhaustedtanning or complementary tanning bath, the tanned leather, skin or peltmay—if desired—be treated with one or more conventional additives e.g.one or more surfactants, preferably as mentioned above as (B), mainly(B1) or (B3), for protecting the grain from damaging friction, or/andwith a preserving agent, preferably as mentioned above as (D).

The tanned leather, skins or pelts produced according to the invention,as described above, may be further treated in conventional way, i.e. maybe drained, dried and mechanically treated as usual for storage and/orshipment.

According to another preferred feature of the invention, the substratesare first tanned in one or two stages with (A), optionally subjected tocomplementary tanning with (F) or (F-II), and then are retanned with(F).

Retanning with (F) may be carried out after having rinsed, dried andoptionally mechanically treated the tanned leather, skin or pelt e.g. inthe dye-house.

The process of the invention may be carried out in a very economic ansimple way, as a pickling and depickling may be omitted, and further thetanning itself may be carried out with a minimum quantity of water, andalso a neutralisation—as otherwise conventionally carried out e.g. aftermetal tanning—is not necessary.

By the process of the invention there may be achieved metal-free tannedleathers, skins or pelts (in particular “wet white” metal-free leathers)of outstanding properties, in particular shrinkage temperatures,softness and consistency, e.g. firm grain texture, and with satisfactoryfastnesses, especially where (A) or respectively (T) is employed for amain or full tanning. If no vegetable tanning agents at all are used orif only white to light yellowish vegetable tanning agents are also used,there may be achieved according to the invention “non-metal whitetanned” leathers, skins and pelts, in particular non-metal “wet white”leathers, of high quality and very light own colour, i.e. nearly white.Where vegetable tanning agents of brownish to reddish colour are alsoused, the shade of the resulting tanned leathers, skins and pelts willbe correspondingly slightly more brownish or reddish. Where (A) isemployed for full tanning or for pre-tanning and main tanning and isfollowed by (F), in particular (F-II), for complementary tanning,further increased shrinkage temperatures T_(S) may be achieved.

The tanned leathers, skins and pelts produced as described are suitablefor further treatment in conventional way, mainly by retanning and/orfatliquoring and optionally dyeing and/or finishing. Fatliquoring may becarried out with known fatliquoring agents. Retanning is preferablycarried out with (F). By retanning them with (F) and fatliquoring theremay be produced upon drying high quality crust leathers. For dyeingthere may be employed known leather dyes (e.g. as defined and inparticular listed in the “Colour Index edited by Society of Dyers andColourists and American Association of Textile Chemists and Colourists”)and there may be obtained dyeings of satisfactory properties, mainlycolour penetration, colour yield and fastnesses. With those leathers,skins or pelts which are of very light own colour, i.e. are nearlywhite, as mentioned above, there may also be achieved dyeings ofdelicate shades (pastel shades) of very pleasant shade. Conventionalleather finishing agents may also be employed for finishing if desired.

Therefore, another subject of the invention is the use of the tannedleather, skins or pelts produced according to the process as describedabove, also with all its preferred embodiments, for further processingby at least one further treatment selected from the group consisting of

-   (a) retanning with a further non-mineral tanning agent (F), which is    different from the tanning agent (A),-   (b) fat-liquoring,-   (c) dyeing, and-   (d) finishing.    preferably a and b and optionally c and/or d.

In the following examples the indicated percentages are by weight; theviscosities are Brookfield rotational viscosities measured at 20 rpmwith spindle nr. 3 at 20° C. unless otherwise indicated.

EXAMPLES Example 1

20 g of 1,4-dichlorophthalazine are charged into a reactor and areheated with stirring to 230° C. At this temperature 15 g of oleum areadded during 15 minutes allowing the temperature to rise to 260° C. andstirring is continued at 240-250° C. for 5 hours and then the mixture iscooled to 80° C. At this temperature 80 g of water and 30 g of aqueous30% sodium hydroxide solution are added and then the mixture is allowedto cool to 25° C.

There is obtained a white-yellowish dispersion (Composition 1)containing the product of formula (1).

which is a mixture of compounds in which the sulpho group is in position5 and in position 6

Example 2

5 g of 1-phenyl-4,5-dichloro-6-pyridazinone are charged into a reactorand the product is heated with stirring to 160° C. At this temperature2.5 g of 98% sulphuric acid are added during 15 minutes allowing thetemperature to rise to 180° C. and stirring is continued at 170-190° C.for 5 hours and then the mixture is cooled to 80° C. At this temperature20 g of water and 4 g of aqueous 30% sodium hydroxide solution are addedand then the mixture is cooled to 25° C.

There is obtained a white-yellowish dispersion (Composition 2)containing the product of formula (2)

which is a mixture of compounds in which the sulpho group is in position4 and in position 2.

Example 3

1,000 g of the Composition 1 obtained according to Example 1 are pre-setat 20 to 25° C. and 10.2 g of disodium hydrogen phosphate, 8.7 g ofmonosodium dihydrogen phosphate and 2.0 g of NIPACIDE® BIT 20 (acommercial biocide based on 1,2-benzothiazolin-3-one of Clariant,Switzerland) are added with stirring. There is obtained awhite-yellowish dispersion (Composition 3).

Example 4

100 g of water are heated to 50 to 55° C. At this temperature 4 g ofhydroxyethylcellulose (having a viscosity of its 2% solution of 5,500mPa·s at 25° C. and a pH of 7.0) are added and stirring is continued for1 hour. There are obtained 104 g of hydroxyethylcellulose solution.

1,000 g of Composition 3 obtained in Example 3 are pre-set at 20 to 25°C. and 103.8 g of the hydroxyethylcellulose solution is added withstirring. There is obtained a white-yellowish suspension (Composition 4)having a viscosity of 1,250 mPa·s at 20° C.

Example 5

Example 3 is repeated with the difference that instead of Composition 1of Example 1 there is employed the same amount of Compositions 2 ofExample 2. There is obtained a white-yellowish dispersion (Compositions5).

Example 6

Example 4 is repeated with the difference that instead of Composition 3of Example 3 there is employed the same amount of Compositions 5 ofExample 5. There is obtained a white-yellowish suspensions (Composition6) having a viscosity of 1,250 mPa·s at 20° C.

In the following Application Examples the indicated percentages—if nototherwise Indicated—refer in Application Examples (B) to the weight ofthe split hide, in Application Examples Aa) and Ca) to the weight of thefleshed hide, in Application Examples Ab), Cb), to the weight of thebated hide, and in Application Example D to the wet weight of the tannedleather. The shrinkage temperature T_(S) is determined according tostandard method IUP 16/ISO 3380-2006. Where a treatment is indicated tobe carried out overnight, this is of 10 to 12 hours. If not otherwiseindicated, pH is increased by addition of aqueous 10% by weight ofsodium formate solution, the % by weight being based on the weight ofthe solution or is lowered by addition of aqueous 10% formic acidsolution, the % by weight being based on the weight of the solution. Thedyes are in commercial form blended with sodium chloride, with a dyecontent of around 60%, “C.I.” stands for “Colour Index”.

Application Example A a) Deliming and Bating

Bovine limed hide (French hide of the weight category 8-12 kg), fleshedand not split is charged into a drum with 200% of water at 25° C., 0.1%of defatting agent (C₁₂₋₁₅ alkanol ethoxylated with 7 mols of ethyleneoxide per mol of alkanol) and 0.2% of an ammonium based deliming agent(ammonium chloride and ammonium sulphate) and drummed for 20 minutes.Then the bath is drained, a fresh bath of 50% of water at 35° C., 0.1%of the above mentioned defatting agent and 0.5% of the above mentionedammonium based deliming agent is charged into the drum and drumming iscontinued for 15 minutes. A further 0.5% of ammonium based delimingagent and 0.8% of a mixture of 70% boric acid and 30% mixed organicacids (adipic, glutaric and succinic acids in even parts) are added anddrumming is carried on for 90 minutes. The pH is 7.8 and the crosssection of the hide is colourless to phenolphthalein. 0.6% of Feliderm®Bate PB1 p (a pancreas enzyme based bate of Clariant, Switzerland) isadded and drumming is continued for 30 minutes and then the bath isdrained. 300% of water is added and drumming is carried on for 15minutes at 35° C. then the bath is drained.

b) Tanning

A fresh bath of 50% water at 20° C. is added and the pH is measured anadjusted to 8. 20% of Composition 1 according to Example 1 is added anddrumming is carried on for 60 minutes, then the bath is heated during120 minutes to 30° C. and drumming is continued overnight at 30-35° C.Then the bath is drained. 300% of water at 20° C. is added and drummingis continued for 20 minutes.

If desired 0.2% of Preventol® WB (a biocide of Bayer, Germany) is addedto the last 300% of water.

Then the bath is drained and the leather discharged and horsed up.

The so obtained leather is then sammied, split and shaved to 1.0 to 1.1mm.

There is obtained a leather with satisfactory properties.

Application Example B a) Deliming and Bating

Bovine limed hide (French hide of the weight category 8-12 kg), fleshedand split to a thickness of 2.4-2.5 mm, is charged into a drum with 200%of water at 25° C., 0.1% of defatting agent (C₁₂₋₁₅ alkanol ethoxylatedwith 7 mols of ethylene oxide per mol of alkanol) and 0.2% of anammonium based deliming agent (ammonium chloride and ammonium sulphate)and drummed for 20 minutes. Then the bath is drained, a fresh bath of50% of water at 35° C., 0.1% of the above mentioned defatting agent and0.5% of the above mentioned ammonium based deliming agent is chargedinto the drum and drumming is continued for 15 minutes. A further 0.5%of ammonium based deliming agent and 0.8% of a mixture of 70% boric acidand 30% mixed organic acids (adipic, glutaric and succinic acids in evenparts) are added and drumming is carried on for 90 minutes. The pH is7.8 and the cross section of the hide is colourless to phenolphthalein.0.6% of Feliderm® Bate PB1 p (a pancreas enzyme based bate of Clariant,Switzerland) is added and drumming is continued for 30 minutes and thenthe bath is drained. 300% of water is added and drumming is carried onfor 15 minutes at 35° C. then the bath is drained.

b) Tanning

A fresh bath of 50% water at 20° C. is added and the pH is 8. 10% ofComposition 1 according to Example 1 is added and drumming is carried onfor 60 minutes, then the bath is heated during 120 minutes to 30° C. anddrumming is continued overnight at 30-35° C.

If desired 0.2% of Preventol® WB (a biocide of Bayer, Germany) is addedto the last 300% of water.

c) Complementary Tanning

Then 2% of Tara (commercial vegetable tanning agent, which is an aqueouscomposition of 50% by weight concentration, based on the weight of thecomposition, of an extract of the pods of Caesalpinia Spinosa) is addedand drumming is continued for 3 hours at 35° C. Then the bath is drainedoff. 300% of water at 20° C. is added and drumming is continued for 30minutes. Then the bath is drained off, the leather is discharged andhorsed up. The so obtained leather is then sammied, split and shaved to1.0 to 1.1 mm.

If desired 0.2% of Preventol® WB is added to the last 300% of water.

There is obtained a leather with satisfactory properties.

Application Example C a) Deliming and Bating

Bovine limed hide (Spanish bull hide of the weight category 30 kg),fleshed and not split is charged into a drum with 200% of water at 25°C., 0.1% of defatting agent (C₁₂₋₁₅ alkanol ethoxylated with 7 mols ofethylene oxide per mol of alkanol) and 0.2% of an ammonium baseddeliming agent (ammonium chloride and ammonium sulphate) and drummed for20 minutes. Then the bath is drained, a fresh bath of 50% of water at35° C., 0.1% of the above mentioned defatting agent and 0.5% of theabove mentioned ammonium based deliming agent is charged into the drumand drumming is continued for 15 minutes. A further 0.5% of ammoniumbased deliming agent and 0.8% of a mixture of 70% boric acid and 30%mixed organic acids (adipic, glutaric and succinic acids in even parts)are added and drumming is carried on for 90 minutes. The pH is 7.8 andthe cross section of the hide is colourless to phenolphthalein indicatorsolution. 0.6% of Feliderm® Bate PB1 p is added and drumming iscontinued for 30 minutes and then the bath is drained. 300% of water isadded and drumming is carried on for 15 minutes at 35° C. then the bathis drained.

b) Tanning

A fresh bath of 50% water at 20° C. is added. The pH is measured andadjusted to 8. 15% of Composition 3 according to Example 3 is added anddrumming is carried on for 60 minutes, then the bath is heated to 30°C., 1% of polyacrylates resin is added and drumming is continuedovernight at 30-35° C. Then the bath is drained off. 300% of water at20° C. is added and drumming is continued for 20 minutes.

If desired 0.2% of Preventol® WB is added to the last 300% of water.

Then the bath is drained off, the leather is discharged and horsed up.

1% of syntan based on sulphomethylated dihydroxydiphenylsulphone reactedwith formaldehyde is added for complementary tanning and drumming iscontinued for 120 minutes and then the bath is drained. 300% of water at20° C. is added and drumming is continued for 30 minutes and then thebath is drained and the leather is discharged and horsed up. The soobtained leather is then sammied and shaved to 2.0 to 2.2 mm. There isobtained a leather with satisfactory properties.

Application Example D

The leather obtained in Application Example C is retanned, fatliquoredand dyed as follows:

The leather is charged into the drum, 200% of water at 25° C. and then0.3% of defatting agent (C₁₂₋₁₅ alkanol ethoxylated with 7 mols ofethylene oxide per mol of alkanol) are added, the drum is switched onand drumming is carried on for 20 minutes. 0.5% acetic acid, diluted1:10 is added and drumming is continued for 20 minutes. The pH is 4.5and the cross section of the leather turns green by testing withBromocresol Green indicator. The bath is drained off. 100% of water at25° C. and then 1.6% of fatliquoring agent (oxy-sulphited fish oil) areadded and drumming is continued for 20 minutes. 5% of a retanning syntanbased on sulphomethylated dihydroxydiphenylsulphone reacted withformaldehyde and 5% of a phenolic syntan (reaction product ofsulphonated phenol with formaldehyde and urea) are added and drumming iscarried on for 2 hours. The bath is allowed to dwell overnight withintermittent drumming for 5 minutes every hour, then 0.5% of formic aciddiluted 1:10 is added and drumming is carried on for 20 minutes, thenthe bath is drained off and the leather is washed with 200% of water.The bath is drained off. 100% of water at 50° C. is added followed by 5%of fatliquoring agents (3.5% alkylsulphosuccinate and 1.5% oxy-sulphitedfish oil) and drumming is continued for 1 hour. After addition of 0.5%of formic acid drumming is carried on for 20 minutes and then the bathis drained off. The leather is rinsed for 5 minutes with 200% of waterat 20° C. The bath is then drained off. 50% of water at 20° C. and 5% ofthe black dye C.I. Acid Black 210 is added and drumming is continued for1 hour, then 200% of water at 50° C. and 1% of formic acid are added anddrumming is continued for 10 minutes, then a further 1% of formic acidis added and drumming is carried on for 20 minutes, then the bath isdrained off. 200% of water at 20° C. and 1.5% of a cationic surfactant2-(8-heptadecenyl)-4,5-dihydro-1,3-bis(2-hydroxyethyl)-1H-imidazoliumchloride are added and drumming is carried on for 15 minutes, then thebath is drained off and the leather is discharged. After 24 hours it isset out, vacuum dried at 60° C. during 2 minutes, dried hanging andstaked. There is obtained a black dyed leather of satisfactoryproperties.

By employing 2% the brown dye C.I. Acid Brown 237 instead of the 5% ofthe black dye C.I. Acid Black 210, there is obtained a brown dyedleather of satisfactory properties.

Analogously as the leather from Application Example C also the leathersobtained according to each of Application Examples A and B are retanned,fatliquored and dyed according to the procedure described in ApplicationExample D.

In the above Application Examples there are obtained leathers ofsatisfactory commercial grade in particular with satisfactory graintightness, texture consistency (e.g. as resulting from some typicalproperties such as tensile strength, tear load and stitch tearresistance), softness, fastnesses and general appearance. In the dyeingexamples there are further obtained dyed leathers of satisfactoryproperties in particular shade, dye penetration and colour yield, andfastnesses of the dyeing.

The invention claimed is:
 1. A process for the production of tannedleather, skin or pelt by non-metal tanning, comprising the step oftanning a bated hide, skin or pelt with a tanning agent (A), the tanningagent (A) being a sulpho-group-containing dichloro-diazine selected fromthe group of consisting of compounds of formula (I)

of formula (II)

of formula (III)

and mixtures thereof, wherein R1 is hydrogen, methyl, methoxy, benzoyl,naphthoyl, mono- or di(C₁₋₄-alkyl)-aminocarbonyl, C₁₋₈alkoxy-carbonyl oroxy-mono- or oligo-(C₂₋₃-alkyleneoxy)-carbonyl R2-(SO₃M)_(n) is aradical of formula

R3 is hydrogen, C₁₋₈-alkyl or C₁₋₈-alkoxy, m is 1 or 2, n is 1 or 2 andM is hydrogen, an alkali metal cation or an ammonium cation, theammonium cation being a protonated tertiary amine or a quaternaryammonium cation, in a tanning bath, the tanning bath having a pH of from6 to 10 at the beginning of tanning step.
 2. A tanning process accordingto claim 1, wherein the bated hide or skin or pelt is subjected totanning with (A) without previous pickling.
 3. A process according toclaim 1, wherein a bated and pickled hide, skin or pelt is depickled toa pH in the range of 6 to 10 before the tanning step.
 4. A processaccording to claim 1, wherein the tanning agent (A) is employed in theform of an aqueous composition (T) free of metal compounds of tanningactivity.
 5. A process according to claim 4, wherein the composition (T)is a composition (T1), the composition (T1) further comprising asurfactant (B) a buffer (C1) or both to keep an acidic to neutral pH. 6.A process according to claim 5, wherein the composition (T1) furthercomprises an agent (D) to protect against the damaging action ofmicroorganisms a polysaccharide-based thickener (E) or a mixturethereof.
 7. A process according to claim 6, wherein the aqueouscomposition (T1) comprises a thickener (E).
 8. A process according toclaim 1, wherein the tanning bath further comprises a buffer (C2) toachieve a nearly neutral to basic pH at the beginning of the tanningstep.
 9. A process according to claim 1, wherein the tanning step withthe tanning agent (A) is a pre-tanning, a main tanning, a full tanningor a pretanning and a main tanning.
 10. A process according to claim 9,wherein a non-mineral tanning agent (F), which is different from thetanning agent (A), is used before, after or together with tanning agent(A) in pre-tanning, in main tanning, in full tanning, or in combinationwith tanning agent (A) in full tanning.
 11. A process according to claim10, wherein the non-mineral tanning agent (F) is selected from the groupconsisting of (F1) a vegetable tanning agent, (F2) a syntan, (F3) asynthetic, semisynthetic or natural resin or polymer, (F4) a tanningnatural oil or modified oil, (F5) a4,6-dichloro-1,3,5-triazin-2-yl-aminobenzene-mono- or di-sulphonic acidsalt and (F6) a tanning oxazolidine.
 12. A process according to claim 9,wherein the skin hide or pelt is tanned with tanning agent (A) in a mainor full tanning and then are subjected to a complementary tanning with anon-mineral tanning agent (F) which is different than tanning agent (A).13. A process according to claim 10, wherein the non-mineral tanningagent (F) is employed in a smaller amount compared with the amount ofthe tanning agent (A).
 14. A tanning agent (A) for a tanning processcomprising a tanning agent (A), the tanning agent (A) being asulpho-group-containing dichloro-diazine selected from the group ofconsisting of compounds of formula (I)

of formula (II)

of formula (III)

and mixtures thereof, wherein R1 is hydrogen, methyl, methoxy, benzoyl,naphthoyl, mono- or di(C₁₋₄-alkyl)-aminocarbonyl, C₁₋₈-alkoxy-carbonylor oxy-mono- or oligo-(C₂₋₃-alkyleneoxy)-carbonyl R2-(SO₃M)_(n) is aradical of formula

R3 is hydrogen, C₁₋₈-alkyl or C₁₋₈-alkoxy, m is 1 or 2, n is 1 or 2 andM is hydrogen, an alkali metal cation or an ammonium cation, theammonium cation being a protonated tertiary amine or a quaternaryammonium cation.
 15. A process according to claim 1, further comprisingat least one further treatment selected from the group consisting of (a)retanning with a non-mineral tanning agent (F), which is different fromthe tanning agent (A), (b) fat-liquoring, (c) dyeing, and (d) finishing.16. A process according to claim 1, further comprising a furthertreatment comprising retanning with a non-mineral tanning agent (F)which is different than tanning agent (A).
 17. A process according toclaim 1, further comprising a further treatment comprising retanningwith a non-mineral tanning agent (F) which is different than tanningagent (A), fat-liquoring and optionally dyeing finishing or both. 18.Tanned leather, skin or pelt made by a process according to claim 1.